A head-mounted display (HMD) may present an immersive virtual environment to a user that may entirely or partially occlude the user's view of the physical environment in which he or she operates. For some HMDs, the user's lack of awareness of the physical environment can pose safety hazards. It may further complicate the user's interaction with the physical environment. Several solutions have been proposed to address these issues. In one solution, the user may simply periodically remove the HMD device to look at the physical environment. In another solution, the HMD displays prominent edges found in the complete physical environment that is visible to the HMD's video cameras. Another solution gives the user the opportunity to toggle back and forth between a view of the complete physical environment and the virtual environment. Another solution uses a picture-in-picture strategy to show information regarding the complete physical environment, set within the virtual environment.